IR refers to infrared light. A television remote control uses IR to send a light signal to the television with instructions for activation. Different IR protocols determine how IR works, which explains why a remote for one television will not operate other televisions. Universal remotes, however, contain codes for different IR protocols that allow them to be programmed for a specific television and additional electronics.
Protocols are identified by the manufacturer that created them. Sony's protocol for IR, whether for one of its televisions or other electronic devices using a remote control, involves transmitting the IR on a set frequency. That frequency needs a preprogrammed receiver to recognise it. Sony's televisions and other devices have that preprogrammed information. When the IR light strikes the television, for example, it responds according to the specific light signal sent for the button pushed by the user. Each button generates a different light signal. Sony's signal derives from 480 kilohertz (kHz) and is 1/12 of the frequency, or 40 kHz. The signal consists of a syn pulse, data code and custom code specifically designed for Sony.
NEC, a global electronics company based in Japan, also has its own protocol for IR. It operates on the same principles as Sony, but uses a different frequency to send different types of codes. It operates on 38 kHz frequency and consists of a syn pulse and two address and command codes.
Another manufacturer of electronics that include televisions, Sharp has its own protocol for IR. It uses a similar frequency to NEC, 38 kHz, but different commands and addresses unique to Sharp.
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